Silver halide grains and photographic emulsions

ABSTRACT

Radiation-sensitive silver halide grains, having ions of the Sulfur Group dispersed throughout the interior of the grains in an amount less than that which, on exposure, promote internal latent image formation, exhibit increased photographic speed. Such silver halide grains are surface sensitive, and can be further surface sensitized with chemical sensitizers. These grains can be used to prepare photographic emulsions and elements. The grains themselves can be prepared using convenient precipitation techniques.

United States Patent Berry et al.

SILVER HALIDE GRAINS AND PHOTOGRAPHIC EMULSIONS [75] Inventors: Chester R. Berry; Salvatore J.

Marino, both of Rochester, NY.

[73] Assignee: Eastman Kodak Company,

Rochester, NY.

[22] Filed: Dec. 2, 1971 [21] Appl. No.: 204,347

[52] US. Cl. 96/108 [51] Int. Cl G03c 1/28 [58] Field of Search 96/108 [5 6] References Cited UNITED STATES PATENTS 3,317,322 5/1967 Porter et al 96/108 Primary Examiner-Norman G. Torchin Assistant Examiner-Richard L. Schilling Attorney-Robert W. Hampton et al.

[57] ABSTRACT Radiation-sensitive silver halide grains, having ions of the Sulfur Group dispersed throughout the interior of the grains in an amount less than that which, on exposure, promote internal latent image formation, exhibit increased photographic speed. Such silver halide grains are surface sensitive, and can be further surface sensitized with chemical sensitizers'. These grains can be used to prepare photographic emulsions and elements. The grains themselves can be prepared using convenient precipitation techniques.

16 Claims, No Drawings SILVER HALIDE GRAINS AND PHOTOGRAPHIC EMULSIONS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to radiation-sensitive materials such as photographic materials, radiographic materials, electron beam sensitive materials, and the like. The invention especially relates to radiation-sensitive silver halide grains and their preparation, to silver halide emulsions and radiation-sensitive elements comprising such silver halide grains and the preparation of the emulsions and elements.

2. Description of the Prior Art In the preparation of high quality photographic materials it is generally necessary to increase the sensitivity of the primitive radiation-sensitive silver halides. Accordingly, it is known that silver halide emulsions can be chemically sensitized by adding sensitizing amounts of certain sulfur compounds during making or finishing as described by Sheppard in U.S. Pat. No. 1,574,944, issued Mar. 2, 1926 and in German Patent 1,009,481, of Gamweidner issued May 29, 1957 with labile sulfur compounds such as thioacetamide.

Conventionally, photographic products may be chemically sensitized with chemical sensitizers, such as with reducing agents; sulfur, selenium or tellurium compounds; gold,platinum or palladium compounds; or a combination of these. Suitable procedures and products are described in Sheppard et al U.S. Pat. No. l,623,499 issued Apr. 5, 1927; Waller et al U.S. Pat. No. 2,399,083, issued Apr. 23, 1946; McVeigh U.S. Pat. No. 3,297,447, issued Jan. 10, 1967 and Dunn U.S. Pat. No. 3,297,466, issued Jan. 10, 1967.

There is, however, a continuing need for increasing the speed of radiation-sensitive silver halides for use in photographic materials, including radiographic materials, electron beam sensitive materials and the like. It is apparent, therefore that it is highly desirable to provide radiation-sensitive silver halide grains, emulsions and elements of increased sensitivity to activating rays.

It is therefore an object of this invention to provide new radiation-sensitive materials having new or improved properties. It is a further objectof the invention to provide novel radiation-sensitive materials having increased sensitivity or speed. It is yet another object of the invention to provide new and improved silver halide grains. It is still a further object of the invention to provide novel silver halide grains having an increased sensitivity. Still another object of the invention is to improve the sensitivity of conventionally chemically sensitized silver halide grains. It is yet another object of the invention to provide new radiation-sensitive silver halide emulsions and elements. It is a further object of the invention to increase the speed and sensitivity of radiation-sensitive silver halide elements and emulsions. A further object of the invention is to provide means of preparing new silver halide grains, silver halide emulsions and silver halide elements having increased photographic speed.

SUMMARY OF THE INVENTION In accordance with this invention, improved radia- 1 in non-internal image sensitizing amounts, i.e., in an amount less than that which effects internal latent image formation upon exposure. Also, the silver halide grains of this invention contain ions of the Sulfur Group substantially uniformly dispersed throughout the interior of the grains in a concentration less than that which produces centers (also termed latent image nucleating centers, electron traps or sites) which promote the deposition of photolytic silver. In a preferred embodiment of the invention the silver halide grains or emulsions are also surface chemically sensitized. The radiationsensitive silver-halide grains are employed in preparing silver halide emulsions and silver halide elements such as, for example, radiographic elements, photographic elements, electron beam sensitive elements, infra-red sensitive elements and the like.

DESCRIPTION OF THE PREFERRED EMBODIMENTS One preferred embodiment of the invention relates to improved surface-radiation sensitive silver halide grains and their preparation. In accordance with this embodiment, silver halide grains are formed in the presence of a Sulfur Group containing compound. Grains of the present type are radiation-sensitive silver halide grains that have ions of the Sulfur Group substantially uniformly dispersed throughout the interior of the grains in an amount less than that which effects internal latent image formation on exposure. Preferably the Sulfur Group containing compound is a labile compound as understood in the photographic art, i.e. one that readily yields a Sulfur Group atom or ion. Sulfur Group should be understood to include sulfur, selenium and tellurium. The Sulfur Group containing compounds which can readily be employed according to the invention are well known in the art, and include chemical compounds that are capable of contributing ions of the Sulfur Group to the precipitated silver halide grains. Suitable compounds are disclosed in U.S. Pat. No. 1,574,944, issued Mar. 2, 1926 and 1,623,499, issued Apr. 5, 1927 of Sheppard, US. Pat. No. 2,399,083 of Waller et al issued Apr. 23, 1946, U.S. Pat. No.'3,297,447 of McVeigh issued Jan. 10, 1967 and U.S. Pat. No. 3,297,446 of Dunn issued Jan. 10, 1967. Illustrative compounds which are capable of contributing ions of the Sulfur Group to precipitated silver halide grains such that the ions are substantially uniformly dispersed throughout the interior of the silver halide grains include: sodium thiosulfate, sodium sulfide, thiourea, di-o-tolyl thiourea, dimethylselenourea, colloidal selenium, tetramethylselenourea, diethylselenide, the thiocarbamides, the selenocarbamides, the tellurocarbamides, allyl isocyanate, thioformamide, allyl isotellurocyanate, potassium tellurocyanate, allyl telluourea, and the like. Mixtures of the Sulfur Group compounds can also be utilized readily and with convenience.

In another embodiment of this invention, there is provided a method for the formation of silver halide grains of the present type. The grains can be prepared by any method that results in introducing ions of the Sulfur Group into the grains during their formation, as long as they are introduced at an amount insufficient to effect internal latent image formation on exposure. Preferably, the grains are formed in the presence of a chemical compound capable of contributing ions of the Sulfur Group to the grains, the compound most desirably being present in a concentration insufficient to contribute the ions in an amount which effects internal latent image formation on exposure. Typically, silver halide grains are formed by mixing a soluble silver salt, generally in the form of a solution such as aqueous silver nitrate, with a soluble halide solution, such as aqueous potassium bromide, in the presence of a Sulfur Group compound of the types described herein. Procedures that are useful for bringing the various ingredients together to form the silver halide grains or crystals include single-jet and double-jet techniques, procedures utilizing automatic proportional central means to maintain specified pAg and pH, procedures utilizing an increase in flow rates to obtain non-dispersed grains as described in Wilgus, U.S. Ser. No. 11,838 filed Feb. 16, 1970, now abandoned, hot nucleation techniques as disclosed in Musliner, U.S. Ser. No. 31,351 filed Apr. 23, 1970, now abandoned, and the like.

The Sulfur Group containing compound can be pres ent in the precipitation or reaction vessel, eg a kettle, or in one of the jet stream solutions during formation of the silver halide grains. Preferably, the grains are formed in accordance with the double-jet technique with the Sulfur Group compound present either in the vessel or in the soluble halide salt solution. In accordance with this procedure, a soluble silver salt solution and a soluble halide salt solution are flowed into a kettle to precipitate silver halide. Preferably, the kettle contains a silver halide peptizer such as gelatin or a synthetic peptizer and a ripening agent such as ammonia. The Sulfur Group compound should be present either in the kettle or in the soluble halide salt solution.

In accordance with the invention, the concentration of the Sulfur Group compound is present in noninternal image sensitizing amounts, i.e. in an amount less than that required to provide sites that promote internal latent image formation upon exposure. Advantageous concentrations are readily determined by routine test, as for example, by preparing a photographic element, exposing the element, bleaching the surface of the silver halide grains, and then developing the element in the presence of an internal developer. The presence of internal latent images will be revealed by their development. The absence of internal development indicates the absence of large aggregates of, for example, Ag S and hence the substantially uniform dispersion of Sulfur Group ions throughout the silver halide grains. Preferably the concentration of the Sulfur Group compound is in an amount so as to provide silver halide grains containing ions of the Sulfur Group in an amount greater than zero and up to about 13 parts per million parts of silver. In a preferred aspect of the invention, th Sulfur Group containing compound is present in an amount of from about 2 to about parts Sulfur Group ion per million parts of silver and preferably from about 3 parts to about 5 parts Sulfur Group ion per million parts of silver. According to the invention the Sulfur Group ions are substantially uniformly and atomically dispersed throughout the silver halide grains and are preferably in their divalent form. Since the Sulfur Group ions are believed to be present in an amount of up to 13 parts per million parts of silver, it is difficult to determine their exact chemical identity as uniformly dispersed. The manner by which the Sulfur Group ions produce increases in speed and gamma remain subject to much speculation.

The invention is generally applicable to most silver halides including silver bromide, silver chloride, silver iodide, silver chlorobromide, silver chlorobrornoiodide, silver brorno-iodide and the like. According to a preferred embodiment of the invention, silver bromide and silver bromoiodide grains, especially bromoiodide grains comprising less than about 3% iodide, are formed in the presence of a Sulfur Group containing compound.

As indicated above, the silver halides can be precipitated in the presence of a peptizer, surfactant or other precipitation aids. The peptizers are added generally to prevent undesirable physical or chemical effects on the grain such as clumping, etc. The precipitation aids or peptizers can be introduced with the respective soluble silver salt and halide salt, or they can be present in the precipitation vessel before precipitation is initiated. In general, the precipitation of photographic silver halides is carried out in the presence of peptizers such as gelatin, synthetic polymeric peptizers such as hydrophilic polymers as disclosed in Perry et al. US. Pat. No. 3,425,836, issued Feb. 4, 1969, acrylyl or methacrylyl histidine polymers such as disclosed in US. Pat. No. 3,419,397, issued Dec. 3 i, 1968, hydrophilic polymers such as disclosed in Whitely et al., US. Pat. No. 3,392,025, interpolymers containing vinylamine units as disclosed in Smith et al., US. Pat. No. 3,415,653, issued Dec. 10, 1968, interpolymers such as disclosed in Hollister, U.S. Ser. No. 701,114 filed Jan. 29, 1968, now US. Pat. No. 3,536,677, entitled Polythiaalkyl Acrylates and Acrylamides and Copolymers Containing Same interpolymers as disclosed in Smith et al., US. Ser. No. 701,084 filed Jan. 29, 1968 now US. Pat. No. 3,615,624, entitled Peptizers for Silver Halide Emulsions Useful in Photography and the like.

The silver halides may be washed in order to remove extraneous soluble salts. The soluble salts may be removed by conventional washing techniques such as chill setting and leaching or the emulsion may be coagulation washed, e.g., by the procedure described in Hewitson et al US. Pat. No. 2,618,556, issued Nov. 18, 1952; Yutzy et al US. Pat. No. 2,614,928, issued Oct. 21, 1952; Yackel U.S. Pat. No. 2,565,418, issued Aug. 21, 1951; Hart et al U.S. Pat. No. 3,241,969, issued Mar. 22, 1966; and Waller et al US. Pat. No. 2,489,341, issued Nov. 29, 1949. Other techniques which can be employed in removing extraneous soluble salts are by use of ion-exchange resins or ultrafiltration washing techniques, preferably in those instances where synthetic peptizers are employed in the formation of the silver halide grains.

in a preferred embodiment of the invention the silver halide grains and/or silver halide emulsions are additionally surface sensitized by a suitable means like chemical sensitization. Chemical sensitization is well known in the art and, as used herein, includes sensitization of the type described in Antoine Hautot and l-Ienri Sauvenier in Science et lndustrie Photographiques vol. XXVIII January 1957, pages l-23 and January 1957, pages 57-65. Such chemical sensitization includes gold or noble metal sensitization; sensitization with a Sulfur Group containing compound such as by a labile sulfur compound or selenium compound, and reduction sensitization, i.e. treatment of the silver halides with a reducing agent which does not appreciably fog the silver halide but introduces small specks of metallic silver onto the silver halide crystal or grain. Combinations of the above types of chemical sensitization may be readily employed, for example sulfur and gold sensitization. Suitable procedures for chemically sensitizing silver halides are described in U.S. Pat. No. 1,623,499 of Sheppard issued Apr. 5, 1927, U.S. Pat. No. 2,399,083 of Waller et al issued Apr. 23, 1946, U.S. Pat. No. 3,297,447 of McVeigh issued Jan. 10, 1967 and U.S. Pat. No. 3,297,446 of Dunn issued Jan. 10, 1967. Illustrative compounds that can be used to furnish the sensitizing moiety include: sodium thiosulfate, allyl thiourea, thiourea, arylthioureas, colloidal selenium, gold chloride, potassium aurate, potassium auriaurite, potassium auricyanide, potassium aurithiocyanate, gold sulfide, gold selenide, gold iodide, potassium chloroaurate, ethylenediamine-bis-gold chloride, ammonium chloroplatinite, i.e. (NI-l,,) PtCl ammonium chloropalladate, i.e. (NH PdCl organic gold sensitizers such as described in U.S. Pat. No. 3,297,446, colloidal selenium, selenoacetone, selenoacetophenone, tetramethylselenourea, N-(B-carboxyethyl)-N, N'-dimethylselenourea, selenoacetamide, diethylselenide, 2-selenopropionic acid, 3- selenobutyric acid, methyl 3-selenobutyrate, allyl isoselenocyanate, dioctylselenourea, and the like. It is also highly desirable to vacuum treat the coated dry photographic emulsion and thereafter treat with hydrogen as described in a U.S. application Ser. No. 174,508 of Babcock et al filed Aug. 24, 1971, now abandoned and entitled Process for Sensitizing Photosensitive Materials and Products Obtained Therefrom said Babcock et al application being a continuation-in-part application of Ser. No. 70,465, filed Sept. 8, 1970, now abandoned.

Another preferred embodiment of this invention relates to radiation-sensitive developing out silver halide emulsions comprising the above described silver halide grains dispersed in a variety of vehicles. The vehicles employed can be the same as the peptizer employed in the precipitation or different. Suitable hydrophilic materials include both naturally-occurring substances such as proteins, for example, gelatin, gelatin derivatives, cellulose derivatives, polysaccharides such as dextran, gum arabic and the like; and synthetic polymeric substances such as water soluble polyvinyl compounds like poly (vinylpyrrolidone), acrylamide polymers and the like.

The photographic emulsion layers and other layers prepared in accordance with the practice of this invention can also contain, either alone orin combination with hydrophilic, water permeable colloids, other synthetic polymeric compounds such as dispersed vinyl compounds such as in latex form and particularly those which increase the dimensional stability of the photographic materials. Suitable synthetic polymers include those described, for example, in Nottorf U.S. Pat. No. 3,142,568 issued July 28, 1964; White U.S. Pat. No. 3,193,386 issued July 6, 1965; Houck et al U.S. Pat. No. 3,062,674 issued Nov. 6, 1962; Houck et al U.S. Pat. No. 3,220,844 issued Nov. 30, 1965; Ream et al U.S. Pat. No. 3,287,289 issued Nov. 22, 1966; and Dykstra U.S. Pat. No. 3,411,911 issued Nov. 19, 1968; particularly effective are those water-insoluble polymers of alkyl acrylates and methyl-acrylates, acrylic acid, sulfoalkyl acrylates or methacrylates, those which have cross-linking sites which facilitate hardening or curing, those having recurring sulfobetaine units as described in Dykstra Canadian Patent 774,054. Accordingly there is provided radiation-sensitive silver halide emulsions comprising silver halide grains of the present types. In a preferred embodiment, the silver halide grains are chemically surface sensitized.

In yet another embodiment of this invention, there is provided radiation-sensitive, developing out silver halide elements comprising a support having thereon at least one radiation-sensitive silver halide layer comprising the silver halide grains described above. Typical supports include cellulose nitrate film, cellulose ester film, poly (vinyl acetal) film, polystyrene film, poly (ethylene terephthalate) fiim, polycarbonate film and related films or resinous materials, as well as glass, paper, metal and the like. Typically, a flexible support is employed, especially a paper support, which can be partially acetylat'ed or coated with baryta and/or an alpha-olefin polymer, particularly a polymer of an alphaolefin containing two to 10 carbon atoms such as polyethylene, polypropylene, ethylenebutene copolymers and the like. I

The photographic layers prepared in accordance with the practice of this invention may contain surfactants such as saponin; anionic compounds'such as the alkyl aryl sulfonates described in Baldsiefen U.S. Pat. No. 2,600,831 issued June 17, 1952; amphoteric compounds such as those described in Ben-Ezra U.S. Pat. No. 3,133,816 issued May 19, 1964; and water soluble adducts of glycidol and an alkyl phenol such as those described in Olin Mathieson British Patent 1,022,878 issued Mar. 16, 1966. I

The photographic layers and emulsions prepared in accordance with the practice of this invention may be coated by various coating procedures including dip coating, air knife coating, doctor blade coating, curtain coating, or extrusion hopper coating. If desired, two or more layers may be coated simultaneously by the procedures described in Russell U.S. Pat. No. 2,761,791 issued Sept. 4, 1956; Hughes U.S. Pat. No. 3,508,947 issued Apr. 28, 1970, or Wynn British Patent 837,095 issued June 9, 1960. Silver halide grains of the subject type can also be used for silver halide layers prepared by vacuum deposition as described in British Patent 968,453, issued Sept. 2, 1964 and Lu Valle et al U.S. Pat. No. 3,219,451 issued Nov. 23, 1965.

The photographic melts and emulsions produced in accordance with the practice of this invention may con- 1 tain the normal addenda useful in photographic materials such as photographic silver halide materials. The addenda can be added to the emulsion at the completion of the precipitation or during the final stages of the precipitation. Typical addenda which may be added are development modifiers, antifoggants and stabilizers, developing agents, hardeners,spectral sensitizers and the like.

The following examples are included for a further understanding of the invention.

EXAMPLE 1 present. Each of A and B is coagulated, washed, dried in the conventional manner and coated on a photographic film support at 35 mg. silver and 65 mg. of gelatin per dm Emulsions similar to A and B are prepared (A and B) with the exception that the emulsions are redispersed after washing and optimally sensitized for 30 minutes at 80C with 20 mg. of sodium thiosulfate/Ag mole and coated on a photographic film support at 35 mg. silver and 65 mg. of gelatin per dm The emulsions are exposed for 45 seconds to a 500 W tungsten light source at 3,000 K and thereafter developed for minutes in Kodak DK 50 Developer. The results are summarized in Table I.

TABLE I EMULSION RELATIVE SPEED GAMMA FOG A 100 1.90 0.04 B 240 2.62 0.04 A l,l80 4.60 0.07 B 1,450 4.10 0.05

Relative speed values indicated herein are a function of the exposure necessary to give a density of 0.3 above background fog, the initial control speed being taken as 100 in each case. The results illustrate that photographic silver halide emulsions comprising the silver halide grains of the invention are generally faster than similar photographic emulsions prepared without Sul fur Group ions uniformly dispersed throughout the silver halide grains.

EXAMPLE 2 TABLE II Thioacetamide Surface Sen- Relative ln KBr Solution sitization Speed Gamma Fog No No 100 2.22 .06 No Yes 417 3.00 .06 Yes No 148 2.50 .05 Yes Yes 525 3.14 .07

The results illustrate that photographic silver halide emulsion which is precipitated in the presence of thioacetamide is faster and of a higher contrast than an emulsion which is not chemically sensitized and does not have Sulfur Group ions uniformly dispersed throughout the grains. The emulsion comprising silver halide grains both chemically sensitized and containing Sulfur Group ions uniformly dispersed throughout the interior of the grains is superior to the prior art conventionally prepared emulsion.

EXAMPLE 3 An ammonia ripened silver bromoiodide emulsion (3.3 mole iodide) (C) is prepared by running an aqueous solution of silver nitrate and an aqueous solution of potassium bromide, potassium iodide and thioacetamide into a solution of gelatin containing ammonia with continuous stirring for 15 minutes at 50C. The concentration of thioacetamide is adjusted so as to provide silver halide grains having uniformly dispersed throughout the interior of the grains about 3.7 parts sulfide ion per million parts of silver. The emulsions are coagulated, wahsed and redispersed. A similar emulsion (D) is prepared with the exception that thioacetamide is not present during the precipitation. Separate portions of each emulsion are optimally surface sensitized with one of the following:

a. sodium thiosulfate (15 mg/m Ag) (E 8! F) b. potassium chloroaurate 15 mg/m Ag) plus sodium thiocyanate (50 mg/m Ag) (G & H) and c. sodium thiocyanate (50 mg/m Ag) plus sodium thiosulfate (15 mg/m Ag) plus potassium chloroaurate (2 mg/m Ag) (1 & J). Each emulsion is coated on a photographic film support at 35 mg silver per dm and 65 mg of gelatin per dm The photographic elements are exposed for 45 seconds to a 500 W tungsten light source at 3,000K and developed for 5 minutes in Kodak DK-50 Developer. The results are summarized in Table III.

TABLE I11 Surface sensitization, 'Ihioaceb time (min)! Relative Emulsion amide temp, 0. speed Gamma Fog es 380 1. 30 06 No 2. 08 O4 15/70 2, 340 3v l2 13 30/ 7 933 2. 82 07 20/60 2, 090 1.65 20 25/60 234 1. 03 09 30/60 ll, 200 3.42 .30 35/60 2,190 3.40 12 The results indicate that an emulsion containing silver halide grains of the present type that are prepared in the presence of thioacetamide (incorporated in the salt solution) is significantly faster than one prepared in the absence of thioacetamide.

EXAMPLE 4 A medium grain silver bromoiodide emulsion is prepared by running a solution of silver nitrate and a solution of dimethylselenourea in an amount to provide silver halide grains having uniformly dispersed throughout about 8.5 parts selenide ion per million parts of silver in 2% minutes at 40C into a solution of gelatin, potassium bromide and potassium iodide. Each emulsion is sensitized for 20 minutes at 60C with 3 mg. potassium chloroaurate, 50 mg. sodium thiocyanate and 12 mg. sodium thiosulfate per silver mole. The emulsions are each washed, coated, exposed and processed (for 5 minutes in Kodak DK-SO Developer) according to the procedure of Example 1. The photographic element comprising the silver bromoiodide emulsion prepared by uniformly dispersing dimethylselenourea throughout the silver halide grains shows a relative speed of a whereas the emulsion precipitated in the absence of dimethylselenourea shows a relative speed of l00.

EXAMPLE 5 A fine grain silver bromide emulsion (L) is prepared by running a solution of silver nitrate and a solution of potassium bromide and thioacetamide into a solution of gelatin and ammonia in 15 minutes at 50C. Two similar emulsions (K) and (M) are prepared with the exception that for one selenourea (M) is substituted for thioacetamide and the other no Sulfur Group ion (K) is uniformly dispersed throughout the AgX grains. Portions of each emulsion are coated on a photographic film support. Additional separate portions are optimally sensitized for 20 minutes at 60C with 4 mg potassium chloroaurate and 50 mg sodium thiocyanate and coated on a photographic film support. The so prepared photographic emulsions are exposed and processed according to the procedure of Example 1. The results are summarized in Table IV.

TABLE IV saarwzs aea W s rsisaesa ti sawesmm zation zation K 100 347 1. 102 479 M 112 380 The results clearly illustrate that surface sensitized silver halide grains prepared in accordance with this invention are substantially faster than those silver halide grains which are merely surface sensitized.

EXAMPLE 6 A silver chlorobromide emulsion (N) is prepared in accordance with the double-jet method by running a solution of silver nitrate and a solution of potassium bromide and potassium chloride into a kettle containing a solution of bone gelatin. A second silver chlorobromide emulsion (O) is prepared in the same manner except that 1 mg thioacetamide is .present in the kettle so as to provide silver halide grains containing about 4 parts sulfide ion per million parts of silver, the sulfide ion being uniformly dispersed throughout the interior of the silver halide grains. A third silver chlorobromide emulsion (P) is prepared as above with the exception that thioacetamide is present in the potassium chloride and potassium bromide solution. Separate portions of the emulsions are optimally sulfur and gold sensitized with sodium thiocyanate (50 mg/mole Ag) plus sodium thiosulfate (l2 mg/mole Ag) plus potassium chloroaurate (3 mg/mole Ag) for minutes at 65C. The emulsions are each coated on a photographic film support at 58 mg silver and 54 mg gelatin per din, exposed for 1 second to a 500 W tungsten light source at 2,650K and thereafter developed for 4 minutes in Kodak Dl9 Developer. The results are summarized in Table V.

TABLE v Surface sensi- Relative Emulsion tization Speed Gamma Fog N 100 0.88 .03 N Yes 3,240 5.40 .08 O 94 0.5 3 .05 0 Yes 3,890 4.50 .08 P 224 1.80 .04 P Yes 3,890 4.47 .06

The results clearly illustrate the advantages obtained by preparing photographic silver halide grains, emulsions and elements in accordance with the invention.

EXAMPLE 7 A silver bromide-emulsion (Q) is prepared in accordance with the double-jet method by running a solution of silver nitrate and a solution of potassium bromide into a kettle containing a solution of bone gelatin maintained at pH 6.0 and pAg 9.0. The kettle temperature is held at 70C and the run time is 42 minutes. The washed emulsion obtained comprises silver halide grains of edge-length of 0.15 to 0.20 mu. Separate portions of the emulsion are optimally sensitized with a. 10 mg sodium thiosulfate/Ag mole for 90 minutes at 55C, and

sodium thiosulfate and 5mg potassium chloroaurate/Ag mole for 60 minutes at 55C. The emulsions are coated on a photographic film support at the rate of l 1 mg silver and 8 mg of gelatin per dm and exposed for 45 seconds to a 500 W tungsten light source at 3,000K and thereafter developed for 5 minutes in Kodak DK-SO Developer. The results are summarized in Table VI.

A silver bromide emulsion (R) is prepared in the manner as (Q) with the exception that 3 mg sodium thiosulfate is present in the kettle so as to provide silver halide grains containing about 3.6 parts sulfide ion per million parts of silver substantially uniformly dispersed throughout the interior of the silver halide grains. Separate portions of the washed emulsion (R) are optimally sensitized with c. 10 mg sodium thiosulfate/Ag mole for 90 minutes at 55C, and

d. 10 mg sodium thiosulfate and 5 mg potassium chloroaurate/Ag mole for 60 minutes at 55C.

The emulsions are coated, exposed and developed as 7 above. The results are summarized in Table VI.

TABLE VI EMULSION RELATIVE SPEED GAMMA FOG o 100 3.12 .03 R 229 3.86 .03 o (a) 135 3.44 .03 R (c) 331 4.10 .03 Q (h) 603 4.70 .04 R (d) 1,159 4.30 .04

1 Control no Sulfur Group ion in kettle 2 Control 3 mg sodium thiosulfate in kettle The results clearly illustrate that photographic emulsions prepared in accordance with the invention are substantially faster than emulsions which are sensitized in the conventional manner.

EXAMPLE 8 A silver bromide emulsion (S) is prepared in the same manner as emulsion (Q) of Example 7. Separate portions of the emulsion are optimally sulfur or sulfur halide grains. Separate portions of the washed emulsion are optimally sulfur or sulfur and gold sensitized with c. 10 mg sodium thiosulfate/Ag mole for 90 minutes at C, and

d. l0 mg sodium thiosulfate and 5 mg potassium chloroaurate/Ag mole for minutes at 60C. The

emulsions are coated, exposed and developed as above. coated on a photographic film support at a coverage of The results are summarized in Table VII. 16 mg Agldm Emulsion 2 TABLE VII Emulsion 2 is prepared and coated in the same manner as given for Emulsion l with the exception that the E S J SPEED $23 ag kettle contains 16 mg sodium thiosulfate (4 mg/Ag T 182 3.58 .03 mole so as to provide silver halide grains containing 2; 1:23 :32 about 4.9 parts sulfide ion uniformly dispersed per mil- S (b) 631 iron parts of silver). 1.000 -60 Emulsion 3 Emulsion 3 is prepared in the same manner as given The results clearly show that substantial speed gains are i E l i 2 i h h exception h h k l obtained by employing silver halide emulsions prewi 40 mg di thi lf (10 /A mole o as pared in accordance with the invention as compared to t o id il h lid rai ontaining about 12.2 h r l in wi h il r h li e grain pr p red parts sulfide ion uniformly dispersed per million parts in the conventional manner. of silver) and with the further exception that the emul- Similar results are obtained upon substituting tellusion is not surface sensitized with dimethylselenourea. rium for selenium. Emulsion 4 Emulsion 4 is re ared and coated in the sam manner EXAMPLE 9 as Emulsion l \sith the exceptions that the kettle con- Six silver bromide emulsions are prepared as follows: tains 2 mg dirnethylseleourea (.5 rug/Ag mole so as to Emulsion l provide silver halide grains containing about 2.7 parts A 1,000 ml aqueous solution (1) containing 680 selenide ion uniformly dispersed per million parts of silgrams of silver nitrate is prepared at C. A 1,000 ml ver) and the emulsion is surface sensitized with 4 aqueous solution (2) containing 480 grams of potas- 25 mg/Ag mole ime hyl l n siurn bromide is prepared at 25C. A kettle is prepared Emulsion 5 containing 100 grams gelatin, 5 ml of l N-potassium Emulsion 5 is prepared and coated in the same manbromide solution and water to 2,000 grams. The soluner as Emulsion 4 with the exception that the kettle tion contained in the kettle is brought to C and the contain 4 mg dimethylselenourea (l mg/ g H1016 88 pH adjusted to 6.0. The kettle solution is heated to 30 to provide 5.3 parts selenide ion uniformly dispersed 70C and solutions (1) and (2) are run into the kettle per million parts of silver). over a period of 38 minutes, the rate of addition being Emulsion 6 potentiometrically controlled to maintain an excess of Em lsion 6 i prepared in h me m n as Em bromide ion concentration equivalent to 0.001 N 30- sion 4 with the exception that the kettle contains 8 tassium bromide solution at 70C. The emulsion is 35 mg/Ag mole dimethylselenourea (2 mg/Ag mole so as cooled to 30C, precipitated and redispersed twice. to provide silver halide grains containing 10.6 parts sel- Gelatin (800 gms) is added and the emulsion diluted enide ion uniformly dispersed per million parts of silwith water to give a weight mole of silver of 4,000 ver). grams. The pH and pAg are adjusted to 6.5 and re- Each of the coated Emulsions 1 through 6 inclusive spectively. The emulsion comprised cubic grains with 40 are exposed in the conventional manner and developed edge-length of approximately 0.2 1.. Portions of the for 4 minutes and for 10 minutes in Kodak D-l9 B Deemulsion are sensitized with (b) 4 mg/Ag mole duneveloper. The results are summarized in Table VIII.

TABLE VIII 4 min. D-19 B 10 min. 13-19 B In0u Relative Relative Emulsion bated speed Gamma Fog speed Gamma Fog 1 (a) 4.1 0.03 1 (a) 13 2.9 0. 04 i (a).. 138 3.8 0.04 l (b) 159 t 0 0. 03 1 (b) us 4.8 0.0 1 (b) 219 3.3 0.04 2 (a). 200 3.8 0. 0 2 (a) 150 3.2 0.03 2 (a) 240 3.0 0.04 2 (b). 232 3.1 0.03 3 {a} 200 3.9 0.04 3 (a) 182 2. 4 0. 05 3 an"..- 240 3.0 0.04 4 (b) 355 2.8 0.06 3 (b) 363 2.0 0.06 5 (him 327 1. 2 0.11 5 (h). 550 1.9 0.06 0 (b). 204 1.1 0. 0s 6 (b) 0. 95 o. 11 0 (0 309 0. 95 0.1

thylselenourea and (a) '75 mg/Ag mole sodium thiosul- Similar results are obtained by uniformly dispersing fate at H and A; 6,5 and 8.5 re e ti l t 65C tellurium throughout the silver halide grains in place of The emulsion is adjusted to a weight per Ag mole of selenium. The results as summarized in Table VIII 6,000 grns containing 300 gms of gelatin/Ag mole and clearly show that silver halide emulsions prepared in accordance with the invention are substantially faster than the conventionally prepared silver halide emul- The results as summarized in Table Vlll evidence remarkable increases in sensitivity with no increase in fog upon dry incubation.

The photographic elements prepared in accordance with the practice of this invention may contain matting agents such as starch, titanium dioxide, zinc oxide, silica, polymeric beads including beads of the type described in Jelley et al U.S. Pat. No. 2,992,101 issued July 11, 1961 and Lynn U.S. Pat. No. 2,701,245 issued; Feb. 1, 1955.

The photographic elements prepared in accordance with the practice of this invention may also contain brightening agents including stilbenes, triazines, oxazoles and coumarin brightening agents. Water soluble brightening agents may be used such as those described in McFall et a1 U.S. Pat. No. 2,933,390 issued Apr. 19, 1960, or dispersions of brighteners may be used such as those described in Oetiker et al U.S. Pat. No. 3,406,070 issued Oct. 15, 1968, and Heidke French Patent 1,530,244.

, The various layers, including the photographic layers prepared in accordance with this invention can contain light absorbing materials and filter dyes such as those described in Sawdey U.S. Pat. No. 3,253,921 issued May 31, 1966. If desired, the dyes can be mordanted, for example, as described in Milton et al U.S. Pat. No. 3,282,699 issued Nov. 1, 1966.

The sensitizing dyes and other addenda added to thephotographic elements prepared in accordance with this invention may be added from water solutions or suitable organic solvent solutions may be used. The compounds can be added using various procedures including those described in Johnson etal U.S. Pat. No. 3,425,835 issued Feb. 4, 1969.

The photographic layers prepared in accordance with this invention can be designed for colloid transfer processes such as described in Yutzy et al U.S. Pat. No. 2,716,059 issued Aug. 23, 1953; silver salt diffusion transfer processes such as described in Land U.S. Pat. No. 2,543,181 issued Feb. 27, 1951; color image transfer processes such as described in Whitmore et al U.S. Pat. No. 3,227,550 issued Jan. 4, 1966; Barr et al U.S. Pat. No. 3,277,551 issued Jan. 4, 1966; Whitmore et al U.S. Pat. No. 3,227,552 issued Jan. 4, 1966; and Land U.S. Pat. No. 3,415,664 issued Dec. 10, 1968; U.S. Pat. No. 3,415,645 issued Dec. 10, 1968; and U.S. Pat. No. 3,415,646 issued Dec. 10, 1968; and imbibition transfer processes as described in Minsk U.S. Pat. No. 2,882,156 issued Apr. 14, 1959.

The photographic melts, emulsions and layers prepared in accordance with this invention may be designed for use with elements designed for color photography, for example, elements containing color-forming couplers such as those described in .lelley et al U.S. Pat. No. 2,322,027 issued June 15, 1943; Barr et al U.S. Pat. No. 3,227,554 issued Jan. 4, 1966; and Graham et al U.S. Pat. No. 3,046,129 issued July 24, 1962; or elements to be developed in solutions containing colorforming couplers such as those described in Schwan et a1 U.S. Pat. No. 2,950,970 issued Aug. 30, 1966; and in false sensitized color materials such as those described in l-lanson U.S. Pat. No. 2,763,549 issued Sept. 18, 1956.

The photographic silver halide emulsion prepared in accordance with the practice of this invention can be used for making lithographic printing plates such as by the colloid transfer of undeveloped and unhardened areas of an exposed and developed emulsion to a suitable support as described in Clark et al US. Pat. No. 2,763,553 issued Sept. 18, 1956; to provide a relief image as described in Woodward U.S. Pat. No. 3,402,045 issued Sept. 17, 1968 or Spencer U.S. Pat. No. 3,053,658 issued Sept. 1 1, 1962; to prepare a relief printing plate as described in Baxter et al U.S. Pat. No. 3,271,150 issued Sept. 6, 1966; to prepare a silver salt diffusion transfer plate as described in Hepher et a] British Patent 934,691 issued Aug. 21, 1963 and Agfa British Patent 883,846 issued Dec. 6, 1961.

The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

We claim:

1. Radiation-sensitive silver halide grains having ions of the Sulfur Group substantially uniformly dispersed throughout the interior of said grains in an amount ranging from about 2 to about 10 parts per million parts of silver; said ions being selected from the group consisting of sulfur ions, selenium ions, tellurium ions, and mixtures thereof.

2. Radiation-sensitive chemically surface sensitized silver halide grains having ions of the Sulfur Group substantially uniformly dispersed throughout the interior of said grains in an amount ranging from about 2 to about 10 parts per million parts of silver; said ions being selected from the group consisting of sulfur ions, selenium ions, tellurium ions, and mixtures thereof.

3. Radiation-sensitive silver halide grains as described in claim 2 wherein the surface sensitizer for said grains is sulfur, selenium or sulfur and gold.

4. Radiation-sensitive silver halide grains as described in claim 2 wherein the Sulfur Group ions comprise sulfur ions.

5. Radiation-sensitive silver halide grains as described in claim 2 wherein the Sulfur Group ions comprise selenium ions.

6. Radiation-sensitive silver halide grains as described in claim 2 wherein the Sulfur Group ions are in said grains in an amount ranging from about 3 to about 5 parts per million parts of silver.

7. Radiation-sensitive silver halide grains as described in claim 2 wherein the silver halide comprises silver bromide, silver chlorobromide, or silver bromoiodide. f

8. A radiation-sensitive element comprising a support having thereon at least one silver halide layer comprising silver halide grains as described in claim 1.

9. A radiation-sensitive element comprising a support having thereon at least one silver halide layer comprising silver halide grains as described in claim 2.

110. A radiation-sensitive element as described in claim 9 wherein said silver halide layer is a silver halide emulsion layer.

11. A radiation-sensitive silver halide emulsion comprising silver halide grains having ions of the Sulfur Group substantially uniformly dispersed throughout the interior of said grains in an amount ranging from about 2 to about 10 parts per million parts of silver; said ions being selected from the group consisting of sulfur ions, selenium ions, tellurium ions, and mixtures thereof.

12. A radiation-sensitive silver halide emulsion as described in claim 11 wherein the silver halide grains are chemically surface sensitized.

13. A radiation-sensitive silver halide emulsion as described in claim 12 wherein the surface sensitizer for said grains is sulfur, a noble metal, or selenium.

14. A process for preparing radiation-sensitive silver halide emulsions comprising silver halide grains having ions of the Sulfur Group substantially uniformly dispersed throughout the interior of said grains in an amount less than that which promotes internal latent image formation on exposure, the process comprising introducing said ions of the Sulfur Group into said grains during their formation in an amount ranging from about 2 to about 10 parts per million parts of silver; said ions being selected from the group consisting of sulfur ions, selenium ions, tellurium ions, and mixtures thereof.

15. A process for preparing radiation-sensitive silver halide emulsions comprising silver halide grains having ions of the Sulfur Group substantially uniformly dispersed throughout the interior of said grains in an amount less than that which promotes internal latent image formation on exposure, the process comprising forming said silver halide grains in the presence of a chemical compound capable of contributing ions of the Sulfur Group to said grains, said chemical compound being present in a concentration sufficient to contribute said ions in an amount of from about 2 parts per million to about 10 parts per million parts of silver; said ions being selected from the group consisting of sulfur ions, selenium ions, tellurium ions, and mixtures thereof.

16. A process as described in claim 15 which further comprises the step of chemically sensitizing said grains. 

2. Radiation-sensitive chemically surface sensitized silver halide grains having ions of the Sulfur Group substantially uniformly dispersed throughout the interior of said grains in an amount ranging from about 2 to about 10 parts per million parts of silver; said ions being selected from the group consisting of sulfur ions, selenium ions, tellurium ions, and mixtures thereof.
 3. Radiation-sensitive silver halide grains as described in claim 2 wherein the surface sensitizer for said grains is sulfur, selenium or sulfur and gold.
 4. Radiation-sensitive silver halide grains as described in claim 2 wherein the Sulfur Group ions comprise sulfur ions.
 5. Radiation-sensitive silver halide grains as described in claim 2 wherein the Sulfur Group ions comprise selenium ions.
 6. Radiation-sensitive silver halide grains as described in claim 2 wherein the Sulfur Group ions are in said grains in an amount ranging from about 3 to about 5 parts per million parts of silver.
 7. Radiation-sensitive silver halide grains as described in claim 2 wherein the silver halide comprises silver bromide, silver chlorobromide, or silver bromoiodide.
 8. A radiation-sensitive element comprising a support having thereon at least one silver halide layer comprising silver halide grains as described in claim
 1. 9. A radiation-sensitive element comprising a support having thereon at least one silver halide layer comprising silver halide grains as described in claim
 2. 10. A radiation-sensitive element as described in claim 9 wherein said silver halide layer is a silver halide emulsion layer.
 11. A radiation-sensitive silver halide emulsion comprising silver halide grains having ions of the Sulfur Group substantially uniformly dispersed throughout the interior of said grains in an amount ranging from about 2 to about 10 parts per million parts of silver; said ions being selected from the group consisting of sulfur ions, selenium ions, tellurium ions, and mixtures thereof.
 12. A radiation-sensitive silver halide emulsion as described in claim 11 wherein the silver halide grains are chemically surface sensitized.
 13. A radiation-sensitive silver hAlide emulsion as described in claim 12 wherein the surface sensitizer for said grains is sulfur, a noble metal, or selenium.
 14. A process for preparing radiation-sensitive silver halide emulsions comprising silver halide grains having ions of the Sulfur Group substantially uniformly dispersed throughout the interior of said grains in an amount less than that which promotes internal latent image formation on exposure, the process comprising introducing said ions of the Sulfur Group into said grains during their formation in an amount ranging from about 2 to about 10 parts per million parts of silver; said ions being selected from the group consisting of sulfur ions, selenium ions, tellurium ions, and mixtures thereof.
 15. A process for preparing radiation-sensitive silver halide emulsions comprising silver halide grains having ions of the Sulfur Group substantially uniformly dispersed throughout the interior of said grains in an amount less than that which promotes internal latent image formation on exposure, the process comprising forming said silver halide grains in the presence of a chemical compound capable of contributing ions of the Sulfur Group to said grains, said chemical compound being present in a concentration sufficient to contribute said ions in an amount of from about 2 parts per million to about 10 parts per million parts of silver; said ions being selected from the group consisting of sulfur ions, selenium ions, tellurium ions, and mixtures thereof.
 16. A process as described in claim 15 which further comprises the step of chemically sensitizing said grains. 